CN102193215A - Wavelength scanning light source - Google Patents
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- CN102193215A CN102193215A CN201110067875XA CN201110067875A CN102193215A CN 102193215 A CN102193215 A CN 102193215A CN 201110067875X A CN201110067875X A CN 201110067875XA CN 201110067875 A CN201110067875 A CN 201110067875A CN 102193215 A CN102193215 A CN 102193215A
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Abstract
The invention belongs to the technical field of a laser light source and relates to a wavelength scanning light source which comprises a multi-wavelength optical fiber laser, an electro-optical switch, a 2*2 3dB directional coupler, a single-side band modulator, a radio-frequency signal generator, a semiconductor light amplifier and an isolator, wherein equal frequency interval multi-wavelength signals output by the multi-wavelength optical fiber laser are input to a primary input port of the directional coupler after passing through the electro-optical switch; a secondary output port of the directional coupler is connected to an input end of the single-side band modulator; the single-side band modulator is modulated by a radio frequency signal output by the radio-frequency signal generator, thereby wholly performing frequency shift of the input multi-wavelength signals; the output end of the single-side band modulator is connected to the isolator after being amplified by the semiconductor light amplifier; and the signal output by the isolator is sent to a circulating input port of the directional coupler. The wavelength scanning light source can be used for increasing the scanning frequency and efficiently solving the problem that the light source scanning frequency is limited due to the low tuning frequency of the existing filter.
Description
Technical field
The present invention relates to the high sweep frequency wavelength-swept source of a kind of high precision, directly apply to key areas such as Fibre Optical Sensor, optical coherence tomography and high-resolution spectro scopy.
Background technology
The length scanning LASER Light Source is a kind of output wavelength repeats continuous sweep in certain spectral range a light source, all will use it in a lot of optics hot spot application and the research system: such as Physical layer---the optical fiber sensing network of known by everybody Internet of Things; Bring optical coherence tomography (OCT) system of tremendous development for biomedical imaging; Lead us better to find out and change intramundane high-resolution spectro scopy technology or the like.Need be input all in these systems, obtain physical message by the feedback signal of reception, detection and analytic system with the length scanning LASER Light Source.Therefore the performance of light source has directly determined the performance index of system.For wavelength-swept source, the spectral range of length scanning, sweep frequency and scanning accuracy are the parameter indexs of three cores, and around these indexs, the researchist has carried out many research both at home and abroad.Typical length scanning LASER Light Source is made of wideband gain medium and fast tunable optical filter.Present existing length scanning LASER Light Source can be divided into the based semiconductor structure and based on two big classes of optical fiber structure.Wavelength-swept source for semiconductor structure serves as typical case's representative with extenal cavity tunable LD, and it can realize hundred nm wavelength tuning ranges and commercialization, but its tuned speed is subject to the influence of body grating velocity of rotation.Wavelength-swept source based on optical fiber structure is a focus of studying at present, and around above-mentioned three core parameters, present present Research and subject matter have:
1. the spectral range of length scanning, the i.e. tunable range of wavelength.In order to make system obtain bigger measurement range or higher spatial resolution, the spectral range of light source should be wide as far as possible.For example in optical fiber sensing network, each grating all will use the spectrum resource of 2～3nm, so the spectral range of light source is wide more, and the grating that can connect in the network is just many more, and the quantity of information that network can obtain is also big more.And for the OCT system, the spatial resolution of its imaging directly and the light source tuning range be inversely proportional to.
At present the wideband gain medium of selecting for use based on the wavelength-swept source of optical fiber structure mainly contains two kinds of Er-doped fiber (EDF) and semiconductor optical amplifier (SOA)s.Can realize output wavelength tuning in～80nm scope based on the scanning light source of EDF, but its service band only limits to 1550nm.And not only can realize tuning in the 100nm scope based on the scanning light source of SOA, also can select the SOA of different gains wave band, thereby be operated in different wave band (as 800nm, 1000nm, 1300nm, 1550nm) according to system's needs.
2. the sweep frequency of light source (cycle), the i.e. frequency (cycle) of the inswept whole work spectral range of wavelength.In order to improve the measuring speed of system, need light source to have to try one's best high sweep frequency.Such as, there is the sensor of magnanimity undoubtedly in the Physical layer of Internet of Things, and in order to realize the high speed dynamic sensitive, the sweep velocity of light source is most important.When particularly using some vibration informations of fiber sensor measuring, require the sweep frequency of light source must be higher than vibration to be measured itself especially, could effectively realize the collection of signal.To three-dimensional OCT system, satisfy the real time imagery in the practical application for another example, the sweep frequency that often requires light source is more than 100kHz.
Two principal elements of restriction light source scanning frequency are: the photon lifetime in the sweep velocity of tunable optic filter and the laser cavity, the latter and chamber grow up to inverse ratio.The tunable FP wave filter that fast tunable optical filter commonly used at present is mainly polygon scanning mirror and is driven by piezoelectric ceramics (PZT), but they all belong to the wave filter of mechanical tuning, and its sweep frequency generally is lower than tens kHz.The Nakamura of 2010 Japanese Anritu companies etc. utilizes the micromechanics scanning mirror to realize the sweep frequency of 307.8Hz in the 160nm wavelength tuning range.The tuning methods that phase ratio micro scanning mirror, PZT drive FP can obtain higher sweep frequency, and at present existing tens---the experiment report of hundred kHz, wherein with the FP best performance of Micron Optics.Though the FP through particular design experimentally can be operated on the level of hundreds of kHz, but the endurance issues of PZT under this higher-order of oscillation pattern is not resolved as yet, so Micron Optics company is also emphasizing on its official website that the user is not used in it under high frequency of hundred kHz.
For second limiting factor, i.e. the long problem in the chamber of laser cavity, solution commonly used is to utilize SOA as gain media rather than EDF, it is long effectively to shorten the chamber like this.In addition, U.S. R.Huber etc. has also proposed the method for Fourier territory locked mode (FDML), be in the chamber sweep time of FP be set in and equal light in the chamber, circulate time or its integral multiple in a week, make laser works under the quasistatic state, reduce of the influence of chamber length to sweep frequency.Utilize FDML to realize the sweep frequency of 290kHz in the 105nm tuning range at present, but so still there is serious endurance issues in PZT under the high frequency.And the required laser cavity of this scheme is long usually at tens km, and this will bring a series of problems such as chromatic dispersion, temperature stability.
Japan Tokyo university proposed a kind of chromatic dispersion tunable technology in 2009, and this method has been saved FP by the realization of the gain/loss in tunable dispersion chamber wavelength tuning, can obtain～sweep frequency of 200kHz.But light source output is pulse signal, and its light source live width has only～the nm level, has had a strong impact on the scanning accuracy of light source, so this class research approach does not form main flow.
3. the scanning accuracy of light source, the i.e. step-length of wavelength tuning.Obviously, the scanning accuracy of light source is high more, and the available detectable signal precision of system is also just high more.When grating sensing, survey the scanning accuracy that 1 ℃ of temperature variation requires 12pm, then require the scanning accuracy of 1.3pm for the STRESS VARIATION of 1 ε.And in high-resolution spectro scopy research, this accuracy requirement may reach inferior pm magnitude.
The raising of light source scanning precision depends on the performance of wave filter itself on the one hand, promptly requires it to have high fineness, and this has proposed acid test to device preparing process undoubtedly, has also increased system cost.On the other hand, the output linewidth of the light source self that narrows realizes that as far as possible single longitudinal mode output also is a research direction.Particularly for being the light source of gain media with EDF, its multimode oscillation, mode hopping and mode competition are the problems that must consider.
Summary of the invention
The present invention is intended to solve the existing problem that the wavelength-swept source scanning accuracy is low, sweep frequency is low, proposes the wavelength-swept source of a kind of high scanning accuracy and high sweep frequency.The present invention utilizes the monolateral band of radio frequency signals drive (SSB) modulator, and one group of multi-wavelength that multi-wavelength optical fiber laser is exported carries out whole tuning acquisition wavelength-swept source.Technical scheme of the present invention is as follows:
A kind of wavelength-swept source comprises: multi-wavelength optical fiber laser, electrooptical switching, 2 * 2 type 3dB directional couplers, single side-band modulator, radio-frequency signal generator, semiconductor optical amplifier and isolator.Four ports of described 2 * 2 type 3dB directional couplers are respectively total input port (a), circulation input port (b), total output port (c) and time output port (d), wherein, total input port of coupling mechanism and total output port are respectively applied for the input of initial multi-wavelength signals and the output of the multi-wavelength signals after the process frequency sweep, and circulation input port and time output port are respectively input end and the output terminals with torus of frequency sweep effect; The equifrequent interval multi-wavelength signals of multi-wavelength optical fiber laser output is through total input port of input directional coupler behind the electrooptical switching, the inferior output port of directional coupler links to each other with the input end of single side-band modulator, single side-band modulator is subjected to the modulation of the radiofrequency signal of radio-frequency signal generator output, make the whole generation of the multi-wavelength signals frequency displacement of input, the output terminal of single side-band modulator is through after the amplification of semiconductor optical amplifier, be connected to isolator, be admitted to the circulation input port of directional coupler behind the signal of isolator output.
As preferred implementation, described multi-wavelength optical fiber laser is used to produce that frequency interval is stable, power spectrum width and initial multi-wavelength signals smooth, narrow linewidth; Described electrooptical switching is used for guaranteeing to finish at wavelength the process of single pass, and initial wavelength is only exported once at total output port of directional coupler.
The present invention utilizes the multi-wavelength output (N) of multi-wavelength optical fiber laser, in conjunction with last suitable electric tuning method, makes up the wavelength-swept source of a high sweep frequency and scanning accuracy.The existing relatively wavelength-swept source of this programme has several significant advantages: at first, to same sweep limit and precision, the frequency of spectrum fractional scanning is N a times of single wavelength scanning, has effectively improved the frequency sweep frequency; Secondly, the present invention adopts the electric tuning mode to carry out length scanning, has avoided the use of mechanical tuning device in the system, can effectively solve the low restriction to the light source scanning frequency of existing filter tuner frequency; Once more, the present invention is tuning to one group of optical maser wavelength integral body of multiple-wavelength laser output, is equivalent to insert outside laser cavity tuner, does not exist in the laser cavity photon lifetime to the restricted problem of tuned frequency; At last, the electricity consumption tuning methods carries out length scanning, the accurate precision of control wave long scan, and high more scanning accuracy is low more to the requirement of electron device responsive bandwidth on the contrary, easy more realization.
Description of drawings
Fig. 1 is the structural representation of the high sweep frequency wavelength-swept source of high precision of the present invention.
Fig. 2 is the fundamental diagram of the high sweep frequency wavelength-swept source of high precision of the present invention.
Among Fig. 1: 1. multi-wavelength optical fiber laser, 2. electrooptical switching, 3. directional coupler, 4. single side-band modulator, 5. radio-frequency signal generator, 6. semiconductor optical amplifier, 7. optoisolator.
Embodiment
Further specify the present invention below in conjunction with accompanying drawing.The structure of the high sweep frequency wavelength-swept source of high precision of the present invention, as shown in Figure 1: four ports of 2 * 2 type 3dB directional couplers 3 are respectively: the total input port of a., b. circulation input port, the total output port of c., d. output port; N equifrequent of multi-wavelength optical fiber laser 1 output be total input port of (100GHz) multi-wavelength signals process electrooptical switching 2 back inputs 2 * 2 type 3dB directional couplers 3 at interval, the inferior output port of coupling mechanism 3 connects monolateral band (SSB) modulator 4 of radio-frequency signal generator 5 modulation, the output terminal of modulator 4 connects the input end of semiconductor optical amplifier 6, the output terminal of semiconductor optical amplifier 6 connects the circulation input port of isolator 7 back input directional couplers 3, and the frequency sweep multi-wavelength signals that obtains is from total output port output of directional coupler 3.
When the present invention works:
The equifrequent interval multi-wavelength signals (N wavelength) of multi-wavelength optical fiber laser output is through total input port of input directional coupler behind the electrooptical switching, part light is directly exported by total output port of coupling mechanism, and remaining inferior output port by coupling mechanism enters and finishes its wavelength tuning in the torus.The work of this wavelength tuning is by radiofrequency signal f
mThe single side-band modulator that drives is finished, and it can make the whole f of generation of light signal of input
mFrequency displacement.The effect of SOA is that energy to signal loss in the length scanning process compensates in the torus.Through the SOA energy compensating signal again by the input of the circulation input port of directional couple, a part is directly exported from total output port, another part enters in the torus circulation once more via inferior circulating port and carries out frequency displacement.Therefore, such one group of multi-wavelength signals is every through torus once, and it will by frequency displacement once promptly realize the whole tuning of its wavelength.Work as wavelength X
1Signal frequency shift to λ
2The position time, then realized the single pass process of wavelength integral body, promptly realized the scanning in the whole scanning wavelength scope.This moment, photoswitch was opened once more, re-entered one group of multi-wavelength signals of original frequency position in torus, the length scanning process of a beginning new round.The effect of electrooptical switching is that the one group of wavelength that has guaranteed in torus by frequency displacement is come before total output port, and one group of initial wavelength that frequency displacement does not take place of multiple-wavelength laser output is turn-offed, and guarantees to have only one group of output that frequency displacement takes place at total output port.After wavelength integral body has been finished scanning process, open switch again and import initial wavelength, restart scanning process.
The present invention utilizes 50 wavelength of interval 100GHz (0.8nm) in the multi-wavelength optical fiber laser output C+L band, becomes the length scanning optical fiber source after tuning, can realize the sweep frequency of 200kHz under the 0.8pm scanning accuracy, wavelength scanning range 40nm.Can solve following problem:
1. solve the existing low problem of wavelength-swept source sweep frequency.
The sweep frequency of existing wavelength-swept source is restricted by filter tuner frequency and laser cavity interior photon lifetimes two of big factor, is difficult to improve.The present invention utilizes the method for spectrum fractional scanning directly to obtain the wavelength-swept source of high sweep frequency, can effectively solve this two big limiting factor: first, in this scanning light source, do not need present wavelength-swept source mechanical tuning wave filter commonly used, avoided of the restriction of the tuned frequency of tuning device own system; The second, the present invention is tuning to one group of optical maser wavelength integral body of multiple-wavelength laser output, is equivalent to insert outside laser cavity tuner, does not exist in the laser cavity photon lifetime to the restricted problem of tuned frequency.
2. solve the existing low problem of wavelength-swept source scanning accuracy.
Existing multi wave length illuminating source has proposed and strict requirement the wave filter self character for improving scanning accuracy, has significantly increased manufacture difficulty and system cost.The present invention utilizes the single side-band modulator of radio frequency signals drive to realize the tuning of wavelength, i.e. scanning can effectively solve when obtaining high scanning accuracy the harsh requirement to performance of filter.Therefore in this programme, scanning accuracy is determined that by radio frequency signal frequency radio frequency signal frequency is low more, and scanning accuracy is high more, and this scheme is extremely low to the performance requirement of a whole set of electronic control device on the principle, but can accurately the scanning accuracy of wavelength be brought up to more than the inferior pm.
Claims (3)
1. wavelength-swept source, comprise: multi-wavelength optical fiber laser, electrooptical switching, 2 * 2 type 3dB directional couplers, single side-band modulator, radio-frequency signal generator, semiconductor optical amplifier and isolator, four ports of described 2 * 2 type 3dB directional couplers are respectively total input port (a), circulation input port (b), total output port (c) and time output port (d), wherein, total input port of coupling mechanism and total output port are respectively applied for the input of initial multi-wavelength signals and the output of the multi-wavelength signals after the process frequency sweep, and circulation input port and time output port are respectively input end and the output terminals with torus of frequency sweep effect; The equifrequent interval multi-wavelength signals of multi-wavelength optical fiber laser output is through total input port of input directional coupler behind the electrooptical switching, the inferior output port of directional coupler links to each other with the input end of single side-band modulator, single side-band modulator is subjected to the modulation of the radiofrequency signal of radio-frequency signal generator output, make the whole generation of the multi-wavelength signals frequency displacement of input, the output terminal of single side-band modulator is through after the amplification of semiconductor optical amplifier, be connected to isolator, be admitted to the circulation input port of directional coupler behind the signal of isolator output.
2. wavelength-swept source according to claim 1 is characterized in that, described multi-wavelength optical fiber laser is used to produce that frequency interval is stable, power spectrum width and initial multi-wavelength signals smooth, narrow linewidth.
3. wavelength-swept source according to claim 1 is characterized in that described electrooptical switching is used for guaranteeing to finish at wavelength the process of single pass, and initial wavelength is only exported once at total output port of directional coupler.
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102638305A (en) * | 2012-03-29 | 2012-08-15 | 南京航空航天大学 | Optical single-side band modulation based optical device measuring method and optical single-side band modulation based optical device measuring device |
| CN103814886A (en) * | 2014-02-19 | 2014-05-28 | 北京交通大学 | Wavelength tuning light bird dispeller |
| CN104218449A (en) * | 2014-02-12 | 2014-12-17 | 中科融通物联科技无锡有限公司 | Light source of high-capacity fiber Bragg grating sensing demodulating system |
| CN104300358A (en) * | 2014-09-22 | 2015-01-21 | 江苏骏龙电力科技股份有限公司 | Narrow linewidth laser light source for wide-range phase continuous frequency sweeping |
| CN105514785A (en) * | 2016-01-08 | 2016-04-20 | 暨南大学 | High-speed linear frequency-sweeping laser source |
| CN107490830A (en) * | 2017-09-12 | 2017-12-19 | 哈尔滨工业大学深圳研究生院 | A kind of high speed swept light source device |
| CN109617617A (en) * | 2019-01-21 | 2019-04-12 | 中国电子科技集团公司第二十九研究所 | A kind of the multiwavelength laser generation system and method for tunable wave length |
| CN110690926A (en) * | 2019-09-17 | 2020-01-14 | 天津大学 | Design method of single-sideband modulation electronic control segmented frequency sweeping source |
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| US20050146780A1 (en) * | 2002-08-30 | 2005-07-07 | Mckinstrie Colin J. | Parametric amplification using two pump waves |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102638305A (en) * | 2012-03-29 | 2012-08-15 | 南京航空航天大学 | Optical single-side band modulation based optical device measuring method and optical single-side band modulation based optical device measuring device |
| CN102638305B (en) * | 2012-03-29 | 2014-10-15 | 南京航空航天大学 | Optical single-side band modulation based optical device measuring method and optical single-side band modulation based optical device measuring device |
| CN104218449A (en) * | 2014-02-12 | 2014-12-17 | 中科融通物联科技无锡有限公司 | Light source of high-capacity fiber Bragg grating sensing demodulating system |
| CN103814886A (en) * | 2014-02-19 | 2014-05-28 | 北京交通大学 | Wavelength tuning light bird dispeller |
| CN104300358A (en) * | 2014-09-22 | 2015-01-21 | 江苏骏龙电力科技股份有限公司 | Narrow linewidth laser light source for wide-range phase continuous frequency sweeping |
| CN105514785A (en) * | 2016-01-08 | 2016-04-20 | 暨南大学 | High-speed linear frequency-sweeping laser source |
| CN107490830A (en) * | 2017-09-12 | 2017-12-19 | 哈尔滨工业大学深圳研究生院 | A kind of high speed swept light source device |
| CN107490830B (en) * | 2017-09-12 | 2020-01-17 | 哈尔滨工业大学深圳研究生院 | High-speed frequency-sweeping light source device |
| CN109617617A (en) * | 2019-01-21 | 2019-04-12 | 中国电子科技集团公司第二十九研究所 | A kind of the multiwavelength laser generation system and method for tunable wave length |
| CN110690926A (en) * | 2019-09-17 | 2020-01-14 | 天津大学 | Design method of single-sideband modulation electronic control segmented frequency sweeping source |
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